Refrigerating apparatus including insulation material



Dec. 3, 1963 J. c. RlLL, JR Q 3,112,624

REFRIGERATING APPARATUS INCLUDING INSULATION MATERIAL Filed Oct. 25, 1961 2 Sheets-Sheet 1 38 IN VEN TOR. John a. R/'//, Jr.

His flomey Dec. 3, 1963 J. c. RILL, JR 3,112,624

REFRIGERATING APPARATUS INCLUDING INSULATION MATERIAL Filed Oct. 25, 1961 2 Sheets-Sheet 2 INVENTOR. John 0. Fill, Jr.

g B [145m His Attorney United States Patent 3,112,624 PEFRlGEPAEWG APPARATU lNClJ-ililll lfl lNSULATIfiN MATERKAL John Frill, $2., Dayton, Shin, assignor to General Motors florporafion, Eetroi'f, Mich, a corporation of Delaware Filed (Pet. 25, 1963, Ser. No. 1 57,5 36 7 Claims. ($1. 624-hl) This invention relates to refrigerating apparatus and more particularly to foam insulated refrigerator cabinet constructions which are superior in insulating quality and low enough in cost for extensive use.

The Bodrnan Patent 1,708,462, issued April 9, 1929, discloses that a cellular structure containing a heavy gas of low conductivity in the cells has good insulating properties. The Munters Patent 2,067,015, issued January 5, 1937, mentions a number of gases for insulation use. Cellular foam resin insulations are disclosed in the Gould Patent 2,106,840, issued February 1, 193 8,and the Sterling Patents 2,629,698 and 2,653,139 respectively issued February 24 and September 22, 1953. No commercially practical insulation resulted from these disclosures. None combined assured long continued superior insulating qualities with a sufficiently low cost to be commercially com petitive. At present, some expensive substantially impervious closed cell foam resins containing and retaining low heat conducting gases have found limited use commercially. They have a high insulating value assured for extended periods but the cost is higher than other insulating materials with which they are in competition. Therefore, their use has been limited to the most expensive refrigerators in areas in which superior insulating qualities are required. Although some less expensive cellular foam resins are available, these are relatively pervious and will not retain the low heat conducting gases for a suficient length of time and therefore are not competitive from a combined insulation and cost standpoint.

It is an object of this invention to provide an insulating construction employing expensive and inexpensive cellular foam resin containing low heat conducting gases in such a Way as to provide a superior insulation at a cost low enough to be competitive.

It is another object of this invention to provide an insulating construction in which such inexpensive relatively pervious cellular foam resin containing low heat conducting gases is sealed to prevent loss of its conducting gases by the expensive substantially impervious cellular foam insulation containing and capable of retaining the low heat conducting gases and to prevent their escape from the inexpensive cellular foam resin.

It is another object of this invention to provide an insulation construction in which a major portion of the insulation is composed of such inexpensive cellular foam resin containing low heat conducting gases and a minor portion is composed of such expensive substantially impervious closed cell foam resin insulation containing low heat conducting gases located so as to seal in the less impervious inexpensive cellular foam resin to prevent the escape of the low heat conduct ng gases.

These and other objects are attained in the forms shown in the drawings in which the cabinet is provided with a generally box-shaped sheet metal inner liner and outer shell which are spamd apart. Generally, the insulation space between the inner liner and outer shell may be filled with foam plastic resin in several different manners. In one form, the back panel is made removable and glass fiber strips are placed around the door opening between the inner liner and outer shell to provide a space in which the refrigerant conduits and the electrical conductors can be laid. This portion closed by the glass fiber strips between the inner liner and the outer shell is then sealed "ice by introducing thereover a layer of the expensive substantially impervious closed cell type of foam resin insulation containing a low heat conducting gas so as to seal the space between the inner and outer liners adjacent the door openings. The remaining space between the inner and outer liners is then filled with the inexpensive partly pervious type of cellular foam resin also containing the low heat conducting gas. Should there be any air ducts provided in the insulation space, these may be sealed by the expensive impervious type of cellular foam plastic resin containing the low "heat conducting gas. The remainder of the insulation space may be sealed with inexpensive foam resin with the exception that it is preferable that around the edges of the removable back panel that the expensive impervious type of foam resin be placed around the periphery adjacent the portion wherein the joints between the back panel and the remainder of the cabinet are located.

in the second form, the joint around the back panel is first sealed with the expensive impervious type of :foam resin containing the low heat conducting gas. The remaining portion of the back insulation space is filled with the inexpensive partially impervious foam plastic resin with the exception of the place wherein the refrigerant conduits extend. The inner liner may then be placed within the outer shell of the cabinet and the remaining walls are also poured with the inexpensive partly pervious foam plastic resin containing low heat conducting gas. The space between the inner liner and the outer shell adjacent the door opening is then filled with the expensive impervious type of foam plastic resin containing the low heat conducting gas which is placed over the inexpensive resin previously introduced so as to sefl the inexpensive resin and prevent the escape of its low heat conducting Thereafter, a plastic breaker strip is placed in the door opening to provide a finished surface for the door opening. After the refrigerant lines connecting the compressor and condenser with the evaporator are connected, the expensive type of foam insulation is introduced in and around the conduits in the insulation to complete the sealing of the inexpensive foam plastic resin. The expensive resin thus prevents the loss of the insulation value of the inexpensive resin and thus maintains a high insulation quality for the life of the refrigerator.

Further objects and advantages of the present invention will be apparent from the following description, reference eing had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a fragmentary vertical sectiond View through the lower portion of a refrigerator taken substantially along lines '11 of FIGURE 2 embodying one form of my invention.

FIGURE 2 is a horizontal sectional view taken substantially along the lines 2-2 of FIGURE 1.

FIGURE 3 is a side vertical sectional view of another form of refrigerator cabinet embodying another form of my invention.

Referring now to the drawings and more particularly to FIGURES l and 2, there is shown an outer sheet metal shell 20 provided with a removable rear wall 22 and a bottom wall 2 2- located above the bottom of the shell providing a space 2s for the machinery compartment which contains a motor compressor unit 28 and a condenser 3b. The outer metal shell 2% includes an inturned flange 32 at the front which is reinforced by a U-shaped configuration 34 around the door opening an. The door opening is closed by a flanged insulated refrigerator door 33 which contacts the inturned flange 32 to effect a seal. Within the outer shell 2% there is spaced a metal inner liner ll} enclosing a refrigerated compartment .2 and an evaporator compartment 44 separated from the refrigerated compartment 42 by a sheet metal Wall 46.

The cabinet may be provided with a centrifugal fan 54 in the rear of the evaporator compartment 44 driven by an electric motor 56. The fan 54 operates within a scroll 58 discharging into an upwardly extending duct 69 in the rear wall within the insulation space. This duct which may be made of sheet metal carries the cold air from the scroll 58 up to the upper portion of the refrigerated cornpartment 42.

To prevent condensation of moisture on the outside surfaces of the cabinet, the inside of the outer shell 29 adjacent the door opening 35 is provided with low wattage electric heaters 58 extending completely around the door opening. These are held in place by some form of adhesive tape. in order that th-se low wattage electric heaters 48 can be reached for inspection or repair, they are covered by removable strips 5%) of glass fiber or mineral wool extending entirely around the door open- These glass fiber strips are held in place by ha"- ing their front portions tucked behind the reinforcing flanges 3 of U-shaped configuration. To seal the insulation space between the inner liner 4i) and outer shell 2i), there is applied directly onto the glass fiber strips St? in the insulation space directly between t e inner liner 4t? and the outer shell 2b a layer of the expensive cross linked closed cell type of plastic foam resin 52 containing a low heat conducting gas. This la er may be made from one to two inches thick. it can be applied with the door opening side of the cabinet face-down with the bac. 22 removed.

The duct 6%, which nay be made of sheet metal, is preferably covered with a layer 62 of the same expensive cross linked closed cell substantially impervious type of foam resin containing the low heat conductive gas in order toseal the duct as and to prevent the escape of gases.

Substantially all of the remainder of the insulation space is filled with the inexpensive type of plastic foam resin s4 containin. a low heat conducting gas. However, before the back panel 22 is applied, there is provided directly beneath the inturned flange 66 at the rear of the outer shell 2t? all around the back opening of the outer shell a continuous deposit of the same expensive substantially impervious plastic foam resin containing the low heat conducting gas. This seals the joint where the removable back panel 22 is connected to the remaining portion of the outer shell. The plastic foam resin es should also be from one to two inches thick to provide an adequate seal to prevent the escape of the low heat conducting gas from the less expensive foam resin 64. The less expensive foam 6 is slightly pervious so that it requires the more expensive foam to seal all possible points of escape of the low heat conducting gas from the less expensive plastic foam resin 6o. Both the plastic foam resins adhere tightly to the outer shell and the inner liner so that a hermetic seal is formed for the inexpensive foam resin The inexpensive foam resin '54 adheres to the expensive foam resin 52., 63 readily so that a united foam mass is provided between the inner liner 4%) and the outer shell 2% to provide adequate support for the inner liner ill.

The sealed motor compressor unit 28 and the condenser 39 are connected by a capillary tube 7%) and the return conduit 72 extending through a notch 74 in the front wall of'the outer shell 2% and through the bottom glass fiber strip 5t beneath the door 3% and rearwardly to the left side of the evaporator compartment connecting with the evaporator vs. The refrigerator switch 78 provided for controlling the sealed motor compressor unit also has a capillary tube 89 extending from its location in the machinery compartment 2. 3, also through the notch 4 into the evaporator compartment 44 and is clamped to the right side of the evaporator 76. Since the tubes extend through the glass fiber, the evaporator 7-6 the entire refrigerating system may be readily removed from the cabinet since no part of the system is embedded in the foam. The glass fiber strips 59 and the refrigerant tubing are covered by ornamental plastic breaker strips 82 which at the bottom are provided with an entrance opening 34 for the evaporator compartment i from the refrigerated compartment 42.

in the refrigerator shown in FIGURE 3, the outer metal shell 1' having an inturned flange 12.3 and a U-shaped frame .5 surrounding the door opening 127 is provided with a metal back wall 129 which may be welded to the adjacent i turned flange if desired. Before the metal inner liner 132 is in erted, the welded joint connecting the wall with the remainder of the outer shell is provided with a thick coating 133 of the expensive, substantially impervious, closed ell, plastic foam or resin. This coating 133 renders the outer shell 121 substantially impervious since it is made of seamless sheet metal of dequate thickness. The back wall 129 is provided with an opening 135 which, during the pouring of the insulation, is closed by a suitable plug. This opening 135 is intended for the refrigerant conduits connecting the sealed motor compressor unit 137, located in the machinery compartment 139 beneath the bottom wall 141 of the outer shell, and the tubular condenser 1433, mounted upon the back wall 329, with the evaporator T45, later to be located within the inside of the inner liner 131. A quantity of the less expensive, less impervious, closed cell, plastic foam resin 147 is introduced onto the bacl; wall 129 preferably with the shell 12?. resting on the back wall 129. The inner liner I131 is then put in place and held in its proper relation to the outer shell shown in FIG- URE 1 by some suitable fixture.

Substant ally all the remaining space between the inner iner 131 a. the outer shell is then filled with another portion of expensive, less i ripervious, plastic foam resin $149 which fills the bottom, top and side Walls be tween the inner liner and outer shell, 131 and 121, as shown in FEGULE 3. However, a space or" about four inc; es is left between this less expensive foam 1- 59 and the inturned 123 of the outer wall 121. The less expensive resin 149 therefore terminates at the line or surface 351. After this less expensive resin M9 is set, there is introduced a srnall amount of the more expensive, more impervious, cross linked, closed cell, plastic foam resin 153 onto the surface 151. After this, the plastic flexible breaker strip 155 is snapped in between the edges of the inner liner 13?. and the outer shell fill surrounding the door opening 127 and the resin 153 foams until it substantially completely fills the space in between the line or surface 153 of the resin and the breaker strip 155. Preferably, the ingredients of the plastic resin foams are introduced slowly enough that no excessive pressures develop so that the walls of the insulation space need only a limited amount of support from fixtures or molds.

The refrigerating system is then installed in the cabinet and the supply and suction conduits 157 and 15% are extended through the aperture 135 in the back wall 129 and the aligning aperture 151 in the inner liner 131 to connect with the evaporator within the inner liner 13-. Prior to making this connection, should the opening in the insulation 347 be not sufiiciently large, it may be made of the size shown in FIGURE 3 by the use of a suitable cutting tool. After this connection is made, the opening in the insulation :7 is sealed by the use of more of the ex ensive type or cross linked, closed cell, plastic foam resin .163. This completes the sealing of the inexpensive foam resin so that the low heat conducting gas contained in the inexpensive foam is sealed in by the metal walls of the outer shell 121 and the inner liner 131 as well as the portions E33, 163 and 153 of the expensive type of foam which is substantially impervious to the low heat conducting gas. The door opening 127 may be closed by a refrigerator door 3%5 which may be insulated by inexpensive and expensive plastic resin foam in a similar manner. That is, the inexpensive foam is enclosed by the outer metal walls and the expensive foam so that the low heat conducting gas will be retained in both foams.

Specific examples of the expensive, cross linked closed cell plastic foam resins 52, 62, 133, 153, and 163 are as follows in parts by weight except where the parts are otherwise indicated:

EXAMPLE 1 Component A Prepolymer F 100 Trifiuoromonochloromethane 20 Component B Polyether C 30 Activator mixture I 29.5

Prepolymer F is composed of:

Polyisocyanate ingredient A 75 Polyether C- 25 Polyisocyanate ingredient A is composed of:

2,4 diisocyanate 80 2,6 diisocyanate 20 Polyether C is composed of Sorbital mols 1 Propylene oxide do Water by weight do .1 OH number 495 Acid .30 Viscosity (cps) at 83 F 7500 EXAMPLE 11 Component A Prepolymer A 100 Trifiuoromonochloromethane Component B Polyester A 60 Activator mixture A 1 Prepolymer A is composed of:

Polyisocyanate ingredient A 75 Polyester A Polyester A is composed of:

Phthalic 'anhydride mols 2 Adipic acid do 18 Lead-as metallic lead by weight percent 0.03 Watermaximum by weight do 0.15 OH No 440 Acid No. max 1.5 Viscosity (cps) at 165 F 2900 Activator mixture A is composed of:

Ethylene glycol 11 Dimethylethanolarnine .25 Emulsifier made up of .5 90% polypropylene glycol. 10% polyethylene glycol.

Specific examples of the less expensive plastic foam resins 64, 147, 149 in parts by weight are as follows:

Tall oil is preferably Emery Industries, Inc. Emtall 672-65 Special Crude Tall Oil. Specifications of 70- rosin acid; 4862% fatty acids; acid value of 105 125, saponification value of l30l50 and 1623% unsaponifiable material Quadrol is a trade marked compound, N, N, N, N, tetrakis ethylenediarnine E 172 is a special crude (impure) grade of 4,4 diphenylmethane diisocyanate, freezing point 43 F.-, NCO percent 30-31, assay percent 88-90%, hydrolyzable chloride 0.2%.

R1 1trichlorfluoromethane LS 20an organosilicone surfactant TMG1,1,3,3 tetramethylguanadine While the embodiments of the present invention as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A refrigerator inc.uding inner and outer metal walls enclosing a storage compartment containing a timid to be maintained at desired temperatures, metal duct means between said inner and outer walls connecting with said storage compartment for circulating fluid from said storage compartment, liquid refrigerant evaporating means associated with said circulating fluid for cooling said fluid and located inside of said outer metal walls, said outer metal walls having an opening therein, compressor and condenser means located outside said outer metal walls, refrigerant conduit means extending from said compressor and condenser means through said opening in said outer metal walls to said evaporating means, a first foamed plastic insulation material containing a low heat conducting gas, said insulation material being located between said inner and outer walls surrounding said metal duct means, said insulation material being partially permeable to said gas, and a second foamed plastic insulation material substantially impervious to said gas located in said opening in said outer metal walls surrounding and sealed to and filling the space between the portion of said refrigerant conduit means and said outer metal walls adjacent said opening.

2. A refrigerator including inner and outer metal Walls enclosing a storage compartment to be maintained at desired temperatures, refrigerant evaporating means within said outer metal Walls for cooling said storage compartment, said outer metal walls having an opening therein, compressing and condensing means located outside said outer metal walls, refrigerant conduit means extending from said compressing and condensing means through said opening in said outer metal walls to said evaporating means, a first foamed plastic insulation material containing a low heat conducting gas located between said inner and outer walls, said first foamed plastic insulating material being partially permeable to said gas, and a second foamed plastic insulation material substantially impervious to said gas in said opening in said outer metal walls sealed to and filling the space between the portion of said refrigerant conduit means and said outer metal walls adjacent said opening.

3. In combination, inner and outer metal walls enclosing a compartment, means for creating'a temperature differential between said compartment and an ambient surrounding the outer walls, one of said walls having an opening therein, said inner and outer walls incorporating except for said opening a first foamed plastic insulation material containing a low heat conducting gas which will not pass through said walls located between said inner and outer walls, said first foamed material being partially permeable to said gas, and a second foamed plastic insulation material substantially impervious to said gas for sealing said opening and confining said gas, said second foamed material filling the space between and sealed to the portion of said walls surrounding said opening.

4. In combination, inner and outer metal walls enclosing a compartment, said walls being provided with a door opening, said inner and outer walls being separated around the periphery of the door opening, a first foamed plastic insulation material containing a low heat conducting gas located between said inner and outer walls saiaesa and being partially permeable to said gas, and a second foamed plastic insulation material substantially impervious to said gas extending around the periphery of said door opening in sealing contact with and filling the space between the adjacent portions of said inner and outer walls for preventing the escape of said gas from said first foamed material, and means for creating a temperature difference between said compartment and t"e ambient surrounding said outer walls.

5. in combination, inner and outer metal walls enclosing a compartment, means for creating a temperature differential between said compartment and an ambient surrounding the outer walls, one of said walls having an opening therein, a first foamed plastic polyurethane material containing a low heat conducting gas and prepared from ingredients including a substantial proportion of an isocyanate and a substantial proportion or" tall oil and being partially permeable to said low heat conducting gas, said first material being located between said inner and outer walls, and a second cross-linked foamed polyurethane material containing a low heat conducting gas and being substantially impervious to low heat conducting gases and sealed to the portion of said walls surrounding said opening and bonded to said first material for sealing said opening and confining the low heat conducting gas in said first material.

6. in combination, inner and outer metal walls enclosing a compartment, means for creating a temperature differential between said compartment and an ambient surrounding the outer walls, one of said Walls having an opening therein, a first foamed plastic polyurethane material containiag a low heat conducting gas and prepared from ingredients including a substantial proportion of an isocyanate and a substantial proportion of tall oil and being partially permeable to said low heat conducting gas, said first material being located between said inner and outer walls, and a second cross-linked foamed poi urethane material containing the same low heat conducting gas as said first material and being substantially impervious to said same low heat conducting gas and sealed ii to the portion of said walls surrounding said opening and bonded to said first material for sealing said opening and confining the low heat conduct ng gas in said first material,

7. in combination, inner and outer metal walls enclosing a compartment, said walls being provided with a door opening, said inner and outer walls being separated around the periphery of the door opening, a first foamed plastic polyurethane material containing a low heat conducting gas and prepared from ingredients including a substantial proportion of an isocyanate and a substantial proportion of tall oil and being partially permeable to said heat conducting gas, said first material being located between said inner and outer walls, and a second crosslinked foamed polyurethane material containing a low heat conducting gas and being substantially impervious to the low heat conducting gases extending around the periphery of said door opening in sealing contact with the adjacent portions of said inner and outer walls ,for preventing the escape of said gas from'said first material, and means for creating a temperature differential between said compartment and the ambient surrounding said outer walls.

References @ited in tr e file of this patent UNITED STATES PATENTS 

3. IN COMBINATION, INNER AND OUTER METAL WALLS ENCLOSING A COMPARTMENT, MEANS FOR CREATING A TEMPERATURE DIFFERENTIAL BETWEEN SAID COMPARTMENT AND AN AMBIENT SURROUNDING THE OUTER WALLS, ONE OF SAID WALLS HAVING AN OPENING THEREIN, SAID INNER AND OUTER WALLS INCORPORATING EXCEPT FOR SAID OPENING A FIRST FOAMED PLASTIC INSULATION MATERIAL CONTAINING A LOW HEAT CONDUCTING GAS WHICH WILL NOT PASS THROUGH SAID WALLS LOCATED BETWEEN SAID INNER AND OUTER WALLS, SAID FIRST FOAMED MATERIAL BEING PARTIALLY PERMEABLE TO SAID GAS, AND A SECOND FOAMED PLASTIC INSULATION MATERIAL SUBSTANTIALLY IMPERVIOUS TO SAID GAS FOR SEALING SAID OPENING AND CONFINING SAID GAS, SAID SECOND FOAMED MATERIAL FILLING THE SPACE BETWEEN AND SEALED TO THE PORTION OF SAID WALLS SURROUNDING SAID OPENING. 